Apparatus for changing the magnification of video graphics prior to display therefor on a TV screen

Video magnification apparatus modifies (shrinks or enlarges) video graphic images in a horizontal and vertical direction during a transfer of video graphics data signals from a graphics memory to a television screen. A first magnification modifying device modifies the magnification of a graphic by a vertical magnification factor by generating graphic line address output signals that selectively prevent a transmission of predetermined horizontal lines of the graphic upon the reception of a vertical magnification factor that is less than unity. The first device also causes a transmission of predetermined horizontal lines of the graphic to be selectively repeated upon the reception of a vertical magnification factor that is greater than unity. A second magnification modifying device is responsive to the transmissions of the horizontal lines of the graphic indicated for transmission by the output signals of the first magnification modifying means for modifying the magnification of the graphic in a horizontal direction by a horizontal magnification factor. The second magnification modifying device selects N predetermined pixels of each received X pixel group that are multiplexed into a transmitting X pixel group for transmission in each output signal of the apparatus for a magnification factor equal to or less than unity. Still further, the second device repeats pixels of each received X pixel group a number of times corresponding to an integer magnification factor that is greater than unity for transmission in each output signal of the apparatus.

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Claims

1. Apparatus for modifying the magnification of a graphic prior to displaying the graphic image on a television receiver comprising:

first magnification modifying means for modifying the magnification of a graphic by a first independent predetermined magnification factor in a vertical direction by generating graphic line address output signals for selectively preventing a transmission of predetermined horizontal lines of the graphic upon the reception of a vertical magnification factor that is less than unity, and for selectively repeating a transmission of predetermined horizontal lines of the graphic upon the reception of a vertical magnification factor that is greater than unity; and
second magnification modifying means responsive to the transmissions of the horizontal lines of the graphic indicated for transmission by the graphic line address output signals of the first magnification modifying means for modifying the magnification of the graphic in a horizontal direction by a second independent predetermined horizontal magnification factor, the second magnification modifying means selecting N predetermined pixels of each received group of X pixels that are multiplexed into a transmitting group of X pixels for transmission in each output signal of the apparatus for a horizontal magnification factor equal to or less than unity, where N.ltoreq.X, and for repeating pixels of each received group of X pixels by a predetermined integer amount corresponding to a horizontal integer magnification factor that is greater than unity for transmission in each output signal of the apparatus.

2. The apparatus of claim 1 wherein the first magnification modifying means comprises:

magnification inverting means for inverting the value of the received first independent vertical magnification factor and generating an output signal representative of the inverted vertical magnification factor; and
multiplying means responsive to the output signal from the magnification inverting means and an input signal representing a number of a horizontal line of the graphic currently being accessed for multiplying the inverted vertical magnification factor by the number of the horizontal line of the graphic to generate an output signal representing a line number of the graphic to be used in a vertical magnification process.

3. The apparatus of claim 2 wherein the first magnification modifying means further comprises a subtractor for subtracting a starting horizontal line number of a graphic being accessed from a current line number being accessed of a display of the television receiver and generating an output signal to the multiplying means representing the number of a horizontal line of a graphic being currently pointed to.

4. The apparatus of claim 1 wherein the second magnification modifying means comprises:

a pixel select Read-Only-Memory (ROM) responsive to a received horizontal fractional magnification value for generating a horizontal fractional magnification output signal indicating which pixels of a group of X pixels are to be used in generating an output signal of the apparatus;
a multiplexer drive ROM responsive to the horizontal fractional magnification output signal and a received integer horizontal magnification value for generating separate coded output signals during sequential multiplexing cycles indicating which received pixels of an incoming group of a plurality of Y pixels are to be multiplexed into which output pixels of an outgoing group of a plurality of Y pixels; and
pixel multiplexing means responsive to the coded output signals from the multiplexer drive ROM and a reception of the incoming group of the plurality of Y pixels for multiplexing predetermined ones of the plurality of Y pixels of the incoming group into predetermined ones of the plurality of Y pixels of the outgoing group during each predetermined cycle to form an apparatus output signal.

5. The apparatus of claim 4 further comprising:

cycle control means responsive to a clock signal for generating a predetermined number of sequential cycle signals for transmission to the multiplexer drive ROM; and
offset control means responsive to a completion of a multiplexing of an incoming group of a plurality of Y pixels into predetermined ones of an outgoing group of a plurality of Y pixels during at least one cycle for generating an offset control signal to the multiplexer drive ROM for skewing the multiplexing of a next incoming group of a plurality of Y pixels to begin filling pixels of the outgoing group of Y pixels when a completed multiplexing of a prior incoming group of Y pixels did not fill all of the pixels of the outgoing group of Y pixels during a last cycle; and
the multiplexer drive ROM is responsive to each cycle signal and the offset control signal for generating a separate predetermined coded output signal to the pixel multiplexing means.

6. The apparatus of claim 4 wherein the multiplexer drive ROM is responsive to a combination of the horizontal fractional magnification output signal from the pixel select ROM and the received horizontal integer magnification value indicating a horizontal magnification of less than unity for generating coded output signals that cause predetermined ones of the pixels in the incoming group of the plurality of Y pixels to be repeatedly multiplexed the amount of times indicated by the horizontal integer magnification value into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer, and the multiplexer drive ROM is responsive to a combination of the horizontal fractional magnification output signal from the pixel select ROM and the received horizontal integer magnification value indicates a horizontal magnification greater than unity for generating coded output signals that cause all of the pixels in the incoming group of the plurality of Y pixels to be multiplexed more than once into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer, and other predetermined ones of the pixels in the incoming group of the plurality of Y pixels to be multiplexed only once into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer as indicated by the horizontal fractional magnification output signal.

7. The apparatus of claim 4 wherein the multiplexer drive ROM further generates a hold control signal for preventing the pixel select ROM from changing the currently provided coded output signals and the reception of a next incoming group of the plurality of Y pixels before a multiplexing of a current incoming group of the plurality of Y pixels is complete.

8. Apparatus for modifying the magnification of a graphic prior to displaying the graphic on a television receiver comprising vertical magnification modifying means comprising:

magnification inverting means for inverting the value of a received vertical magnification factor and generating an output signal representative of the inverted vertical magnification factor, where the vertical magnification factor can comprise fractional and integer values;
multiplying means responsive to the output signal from the magnification inverting means and an input signal representing a number of a horizontal line of the graphic currently being accessed for multiplying the inverted magnification factor with the number of the horizontal line to generate an output signal representing a line number of the graphic to be accessed; and,
a subtraactor for subtracting a starting horizontal line number of a graphic being accessed from a current line number of a display of the television receiver being accessed and generating an output signal to the multiplying means representing the number of a horizontal line of a graphic being currently pointed to.

9. The apparatus of claim 8 wherein the apparatus further comprises horizontal magnification modifying means comprising:

a pixel select Read-Only-Memory (ROM) responsive to a received horizontal fractional magnification value for generating a horizontal fractional magnification output signal indicating which pixels of a group of a plurality of X pixels are to be used in generating an output signal of the apparatus;
a multiplexer drive ROM responsive to the horizontal fractional magnification output signal and a received integer magnification value for generating separate coded output signals during sequential multiplexing cycles indicating which received pixels of an incoming group of a plurality of Y pixels are to be multiplexed into which output pixels of an outgoing group of a plurality of Y pixels; and
pixel multiplexing means responsive to the coded output signals from the multiplexer drive ROM and a reception of the incoming group of the plurality of Y pixels for multiplexing predetermined ones of the plurality of Y pixels of the incoming group into predetermined ones of the Y pixels of the outgoing group during each predetermined cycle to form an apparatus output signal.

10. The apparatus of claim 9 further comprising:

cycle control means responsive to a clock signal for generating a predetermined number of sequential cycle signals for transmission to the multiplexer drive ROM; and
offset control means responsive to a completion of a multiplexing of an incoming group of a plurality of Y pixels into predetermined ones of an outgoing group of a plurality of Y pixels during at least one cycle for generating an offset control signal to the multiplexer drive ROM for skewing the multiplexing of a next incoming group of a plurality of Y pixels to begin filling pixels of the outgoing group of the plurality of Y pixels when a completed multiplexing of a prior incoming group of a plurality of Y pixels did not fill all of the outgoing pixels of the outgoing group of the plurality of Y pixels during a last cycle; and
the multiplexer drive ROM is responsive to each cycle signal and the offset control signal for generating a separate predetermined coded output signal to the pixel multiplexing means.

11. The apparatus of claim 9 wherein the multiplexer drive ROM is responsive to a combination of the horizontal fractional magnification output signal from the pixel select ROM and the received horizontal integer magnification value indicating a magnification of less than unity for generating coded output signals that cause predetermined ones of the pixels in the incoming group of the plurality of Y pixels to be multiplexed only once into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer, and the multiplexer drive ROM is responsive to a combination of the horizontal fractional magnification output signal from the pixel select ROM and the received horizontal integer magnification value indicating a magnification greater than unity for generating coded output signals that cause all of the pixels in the incoming group of the plurality of Y pixels to be repeatedly multiplexed the amount of times indicated by the horizontal integer magnification value into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer, and other predetermined ones of the pixels in the incoming group of the plurality of Y pixels to be multiplexed only once into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer as indicated by the horizontal fractional magnification output signal.

12. The apparatus of claim 9 wherein the multiplexer drive ROM further generates a hold control signal for preventing the pixel select ROM from changing the currently provided coded output signals and the reception of a next incoming group of the plurality of Y pixels before a multiplexing of a current incoming group of the plurality of Y pixels is complete.

13. Apparatus for modifying the magnification of a graphic prior to displaying an image of the graphic on a television receiver comprising a horizontal magnification modifying means comprising:

a pixel select Read-Only-Memory (ROM) responsive to a received horizontal fractional magnification value for generating a horizontal fractional magnification output signal indicating which pixels of an incoming group of a plurality of X pixels are to be used in generating an output signal of the apparatus;
a multiplexer drive ROM responsive to the horizontal fractional magnification output signal and a received horizontal integer magnification value for generating separate coded output signals during sequential multiplexing cycles indicating which received pixels of an incoming group of a plurality of Y pixels are to be multiplexed into which output pixels of an outgoing group of a plurality of Y pixels; and
pixel multiplexing means responsive to the coded output signals from the multiplexer drive ROM and a reception of the incoming group of the plurality of Y pixels for multiplexing predetermined ones of the plurality of Y pixels of the incoming group into predetermined ones of the plurality of Y pixels of the outgoing group during each predetermined cycle to form an apparatus output signal.

14. The apparatus of claim 13 further comprising:

cycle control means responsive to a clock signal for generating a predetermined number of sequential cycle signals for transmission to the multiplexer drive ROM; and
offset control means responsive to a completion of a multiplexing of an incoming group of a plurality of Y pixels into predetermined ones of an outgoing group of a plurality of Y pixels during at least one cycle for generating an offset control signal to the multiplexer drive ROM for skewing the multiplexing of a next incoming group of a plurality of Y pixels to begin filling pixels of the outgoing group of a plurality of Y pixels when a completed multiplexing of a prior incoming group of a plurality of Y pixels did not fill all of the outgoing pixels of the outgoing group of a plurality of Y pixels during a last cycle; and
the multiplexer drive ROM is responsive to each cycle signal and the offset control signal for generating a separate predetermined coded output signal to the pixel multiplexing means.

15. The apparatus of claim 13 wherein the multiplexer drive ROM is responsive to a combination of the horizontal fractional magnification output signal from the pixel select ROM and the received horizontal integer magnification value indicating a magnification of less than unity for generating coded output signals that cause predetermined ones of the pixels in the incoming group of the plurality of Y pixels to be multiplexed only once into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer, and the multiplexer drive ROM is responsive to a combination of the horizontal fractional magnification output signal from the pixel select ROM and the received horizontal integer magnification value indicating a magnification that is greater than unity for generating coded output signals that cause all of the pixels in the incoming group of the plurality of Y pixels to be repeatedly multiplexed the amount of times indicated by the horizontal integer magnification value into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer, and other predetermined ones of the pixels in the incoming group of the plurality of Y pixels to be multiplexed only once into sequential pixels in the outgoing group of the plurality of Y pixels in the pixel multiplexer as indicated by the horizontal fractional magnification output signal.

16. The apparatus of claim 13 wherein the multiplexer drive ROM further generates a hold control signal for preventing the pixel select ROM from changing the currently provided coded output signals and the reception of a next incoming group of the plurality of Y pixels before a multiplexing of a current incoming group of the plurality of Y pixels is complete.

17. The apparatus of claim 13 further comprising vertical magnification modifying means comprising:

magnification inverting means for inverting the value of a received vertical magnification factor and generating an output signal representative of the inverted vertical magnification factor; and
multiplying means responsive to the output signal from the magnification inverting means and an input signal representing a number of a horizontal line of the graphic currently being accessed for multiplying the inverted vertical magnification factor with the number of the horizontal line to generate an output signal representing a line number of the graphic to be accessed.

18. The apparatus of claim 17 wherein the first magnification modifying means further comprises a subtractor for subtracting a starting horizontal line number of a graphic being accessed from a current line number of a display of the television receiver being accessed and generating an output signal to the multiplying means representing the number of a horizontal line of a graphic being currently pointed to.

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Patent History
Patent number: 5838296
Type: Grant
Filed: Aug 31, 1995
Date of Patent: Nov 17, 1998
Assignee: General Instrument Corporation (Horsham, PA)
Inventors: Donald S. Butler (Scottsdale, AZ), Richard S. Amano (Scottsdale, AZ)
Primary Examiner: Chanh Nguyen
Law Firm: Volpe and Koenig, P.C.
Application Number: 8/523,789
Classifications
Current U.S. Class: 345/127; 345/131
International Classification: G09G 500;